Unlock Super Flag Achievements
#1 - Find every single HP-Up Heart.
#2 - Collect every sticker type in the world.
#3 - Make all of the secret doors appear.
#4 - Collect all of the Comet Pieces.
#5 - Spend 10,000 or more Coins at shops.
#6 - Get a Perfect Bonus (win without getting hit) in 500 or more battles.
#7 - Perform 1,000 or more "Excellent" Action Commands in battle.
#8 - Get three symbols matched on the Battle Spinner slots 50 times.

Unlock Hidden Song at the End
After beating the game (and watching the credits), the screen will shift to the book from the start of the game. The book closes and the light turns off. At this point, just wait about three minutes. A hidden lullaby song will start to play, and will continue to play until you hit a button.